The present invention relates to a lapping tool used for lapping of a surface of a substrate of a magnetic head used in hard disk drive, an optical connector ferrule used in optical fiber connection, etc., which is made of different materials, and a method of manufacturing the same.
An improvement in areal recording density is desired in hard disk drives, and in order to attain this, a flying height of a magnetic head relative to a magnetic recording medium is needed to be further decreased from about 10 nm at present. In order to realize a decrease in flying height, it is essential that a slider surface (air bearing surface) of a magnetic head arranged in opposition to a rotating magnetic recording medium be subjected to very smooth surface finishing with further high accuracy.
Generally, magnetic heads are fabricated in the following manner. That is, Al2O3 (alumina, film thickness of 2 to 10 μm) as an insulation film is formed on a hard substrate made of Al2O3—TiC (alumina titanium carbide), etc., a magnetic device part composed of a shield layer, a gap film, a magnetoresistive film, etc., a lower magnetic pole, an upper magnetic pole, an overcoat (alumina layer) are successively laminated thereon. The structure described above is formed on a 5-inch size substrate by means of thin film processing, in which lithography is used.
Thereafter, a diamond wheel is used to cut the substrate into reed-shaped pieces having a length of 2 inches. After strain after cutting is removed by the use of a method such as both face lapping, etc., a surface perpendicular to the structure laminated on the substrate is subjected to lapping with high accuracy to form a slider surface (air bearing surface) of a magnetic head opposed to a magnetic recording medium, and small pieces including individual magnetic device parts are cut out from the reed-shaped piece to complete a magnetic head.
Generally, in a method of lapping such reed-shaped piece, a reed-shaped piece 14 bonded to a lapping jig is depressed against and slid on a lapping tool 12, which is made of a soft metal to grip abrasive grains (fixed abrasive grains) composed of diamond grains and rotates as shown in FIG. 1, while a hydrocarbon lubricating liquid 13 is dripped on the lapping tool, whereby working, in which a depth of cut is actually small, is performed, and thus working is performed to obtain a smooth surface.
FIG. 2 shows a lapping tool 12 and abrasive grains (fixed abrasive grains) 11 composed of diamond grains and fixedly forced into by mechanical pressures, and a height of an abrasive grain (fixed abrasive grain) 11 projecting from a surface of the lapping tool 12 is called cutting edge height 21.
Lapping conditions include the case where a lapping jig with a reed-shaped piece bonded thereto is rotated and revolved relative to a rotating lapping tool, the case where a reed-shaped piece is oscillated in a direction perpendicular to a rotational direction of a lapping tool, or in parallel to the rotational direction, or the like, details of which are described in JP-A-7-132456.